use the stack

Author: rhooper

shared-bindings/_pixelbuf/PixelBuf.c

@@ -309,6 +309,16 @@ STATIC mp_obj_t pixelbuf_pixelbuf_subscr(mp_obj_t self_in, mp_obj_t index_in, mp
 
         size_t length = common_hal__pixelbuf_pixelbuf_get_len(self_in);
         mp_seq_get_fast_slice_indexes(length, index_in, &slice);
+        static mp_obj_tuple_t flat_item_tuple = {
+            .base = {&mp_type_tuple},
+            .len = 0,
+            .items = {
+                mp_const_none,
+                mp_const_none,
+                mp_const_none,
+                mp_const_none,
+            }
+        };
 
         size_t slice_len;
         if (slice.step > 0) {
@@ -335,8 +345,8 @@ STATIC mp_obj_t pixelbuf_pixelbuf_subscr(mp_obj_t self_in, mp_obj_t index_in, mp
             if (num_items != slice_len && num_items != (slice_len * common_hal__pixelbuf_pixelbuf_get_bpp(self_in))) {
                 mp_raise_ValueError_varg(translate("Unmatched number of items on RHS (expected %d, got %d)."), slice_len, num_items);
             }
-
-            common_hal__pixelbuf_pixelbuf_set_pixels(self_in, slice.start, slice.step, slice_len, value, num_items != slice_len);
+            common_hal__pixelbuf_pixelbuf_set_pixels(self_in, slice.start, slice.step, slice_len, value,
+                num_items != slice_len ? &flat_item_tuple : mp_const_none);
             return mp_const_none;
             #else
             return MP_OBJ_NULL; // op not supported

shared-bindings/_pixelbuf/PixelBuf.h

@@ -47,6 +47,6 @@ void common_hal__pixelbuf_pixelbuf_fill(mp_obj_t self, mp_obj_t item);
 void common_hal__pixelbuf_pixelbuf_show(mp_obj_t self);
 mp_obj_t common_hal__pixelbuf_pixelbuf_get_pixel(mp_obj_t self, size_t index);
 void common_hal__pixelbuf_pixelbuf_set_pixel(mp_obj_t self, size_t index, mp_obj_t item);
-void common_hal__pixelbuf_pixelbuf_set_pixels(mp_obj_t self_in, size_t start, mp_int_t step, size_t slice_len, mp_obj_t* values, bool flattened);
+void common_hal__pixelbuf_pixelbuf_set_pixels(mp_obj_t self_in, size_t start, mp_int_t step, size_t slice_len, mp_obj_t* values, mp_obj_tuple_t *flatten_to);
 
 #endif  // CP_SHARED_BINDINGS_PIXELBUF_PIXELBUF_H

shared-module/_pixelbuf/PixelBuf.c

@@ -230,22 +230,21 @@ void _pixelbuf_set_pixel(pixelbuf_pixelbuf_obj_t* self, size_t index, mp_obj_t v
     _pixelbuf_set_pixel_color(self, index, r, g, b, w);
 }
 
-void common_hal__pixelbuf_pixelbuf_set_pixels(mp_obj_t self_in, size_t start, mp_int_t step, size_t slice_len, mp_obj_t* values, bool flattened) {
+void common_hal__pixelbuf_pixelbuf_set_pixels(mp_obj_t self_in, size_t start, mp_int_t step, size_t slice_len, mp_obj_t* values,
+    mp_obj_tuple_t *flatten_to)
+{
     pixelbuf_pixelbuf_obj_t* self = native_pixelbuf(self_in);
     mp_obj_iter_buf_t iter_buf;
     mp_obj_t iterable = mp_getiter(values, &iter_buf);
     mp_obj_t item;
     size_t i = 0;
-    mp_obj_tuple_t *tuple;
-    uint bpp = self->bytes_per_pixel;
-    if (flattened) {
-        tuple = MP_OBJ_TO_PTR(mp_obj_new_tuple(bpp, NULL));
-    }
+    bool flattened = flatten_to != mp_const_none;
+    if (flattened) flatten_to->len = self->bytes_per_pixel;
     while ((item = mp_iternext(iterable)) != MP_OBJ_STOP_ITERATION) {
         if (flattened) {
-            tuple->items[i % bpp] = item;
-            if (++i % bpp == 0) {
-                _pixelbuf_set_pixel(self, start, tuple);
+            flatten_to->items[i % self->bytes_per_pixel] = item;
+            if (++i % self->bytes_per_pixel == 0) {
+                _pixelbuf_set_pixel(self, start, flatten_to);
                 start+=step;
             }
         } else {